This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The AMBER force field has been widely used for simulating nucleic acid polymers (DNA, RNA) employing the parameters developed principally by Dr. Cheatham. Because of the ability of our GLYCAM parameters to accurately model carbohydrate rings, he has asked us to extend our parameters to nucleic acids. This is a major project, but has the potential to overcome some long-standing weaknesses in the AMBER parameters.